CDI
- CD-i
- CDI College
- CDI Corporation
- CREST Depositary Interest
- California Department of Insurance
- Camperdown Dairy International
- Capacitive deionization
- Capacitor discharge ignition
- Carbonyldiimidazole
- Category Development Index
- Cellular Dynamics International
- Center for Defense Information
- Center for Digital Inclusion
- Centrist Democrat International
- Chak De! India
- Chief of Defence Intelligence
- Child Development Index
- China Development Institute
- Churchill Downs Incorporated
- Ciudad de las Ideas (conference)
- Clinical documentation improvement
- Clostridioides difficile infection
- Coherent diffraction imaging
- Collège des Ingénieurs
- Color doppler
- Combined drug intoxication
- Comisión Nacional para el Desarrollo de los Pueblos Indígenas
- Common direct injection
- Common rail
- Contact-dependent growth inhibition
- Contexts and Dependency Injection
- Contrat à durée indéterminée
- Control Data Institute
- Controlled Demolition, Inc.
- Course deviation indicator
- Current density imaging
- Custodial Detention Index
- Customer data integration
- Cyclin-dependent kinase inhibitor protein
- Cyrel Digital Imager
- Côte d'Ivoire
- DiscJuggler
- Registry of Interpreters for the Deaf
- Roman numerals